(1) "i" as in "sino" is pronounced "ai"
(2) "i" as in "Imax" is pronounced as "ai"
(3) "i" as in "Sinomax" (a brand name of pillows) is pronounced as "i"
(4) "i" as in Isabella" is pronounced as "i"

I once heard that if "i" is separated with a vowel by a consonant, such is sino, "i" is pronounced as "ai". However, I cannot see the rule in examples (3) and (4). I wonder if it's because (3) and (4) are names; therefore, it does not apply.

Does anyone know about this? Thank you.